AFAIK, once x86 didn't supported due to floating point related
On Tue, Jan 4, 2011 at 22:44, Dave Hylands <dhylands@xxxxxxxxx> wrote:
> That is correct. In some architectures, attempts to use floating point
> from the kernel will work. I've seen some x86 code that uses it.
registers are not correctly (or even doing?) saved and restored during
context switching. So maybe it is fixed now...
--
I've often wondered about this oft-cited kernel behaviour too, in my naivety. I understand
that this must be on a per-arch basis, but does this mean that the kernel doesn't police FP
access at _all_ (perhaps this is what Mohit means too)? Does code like X for example have to access it directly, or does it just use the GPU? What about other user-space code - does it
have a separate library and do its own security? Video drivers?
Sorry if these are basic questions, I grepped for float in the kernel but as-yet the associated
code looks really arcane to me - if anyone could answer any of these questions generally
(if that's possible) that would be very helpful with visualizing the mechanism.
Maybe I'm looking in the wrong place.
When I started looking at the kernel I imagined this small, neat, concise piece of highly
efficient code so I wasn't surprised there was no float (don't laugh - how one learns :-/ ) ...
I suppose any float per-arch 'hacks' (to get a larger word size) would not be worth
the overhead of the mode switch and extra code?
Thanks
Julie
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